1. Field of the Invention
The present invention relates to a ventilation member configured to be attached to an opening of a housing.
2. Description of Related Art
Conventionally, for example, in automobile electric components such as automobile lamps and ECUs (Electrical Control Units), OA (office automation) equipment, household electric appliances, and medical devices, a housing containing an electric component or a control board is provided with an opening for the purpose of reducing pressure variation in the housing caused by temperature change or allowing replacement of air in the housing, and a ventilation member is attached to the opening. The ventilation member ensures ventilation between the inside and outside of the housing, and also prevents foreign matters such as dust and water from entering the housing. Examples of such a ventilation member are disclosed in JP 2007-87929 A and JP 2007-87666 A.
For example, JP 2007-87929 A discloses a ventilation member 100 as shown in FIG. 6. The ventilation member 100 is composed of a tubular cover component 101 having a bottom, a tubular body 102 made of rubber, and a gas-permeable membrane 103. The tubular body 102 has a slightly smaller diameter than the cover component 101, and the gas-permeable membrane 103 is disposed so as to close one opening of the tubular body 102. The tubular body 102 is fitted into the cover component 101 by inserting the portion of the tubular body 102 on the gas-permeable membrane 103 side into the cover component 101. Thus, a ventilation path 104 is formed between the inner peripheral surface of the cover component 101 and the outer peripheral surface of the tubular body 102 and between the bottom surface of the cover component 101 and the gas-permeable membrane 103. An opening portion 150a formed in a housing 150 is inserted in the tubular body 102, and thus the ventilation member 100 can be attached to the housing 150.
As shown in FIG. 7 and FIG. 8, a ventilation member 200 disclosed in JP 2007-87666 A includes an inner member 202 on which a gas-permeable membrane 203 is disposed, and a protecting portion 201 fitted to the inner member 202 so as to cover the gas-permeable membrane 203. A plurality of opening portions 201a are formed in the top or side of the protecting portion 201. Such a ventilation member 200 is fixed to an opening portion 250a of a housing 250 via a sealing member 205. A gas having permeated the gas-permeable membrane 203 passes through the opening portions 201a of the protecting portion 201, as a result of which ventilation between the inside and outside of the housing 250 can be ensured. The protecting portion 201 prevents the gas-permeable membrane 203 from being damaged by an external force, and prevents the gas permeability of the gas-permeable membrane 203 from being reduced by accumulation of dust.